This invention relates to an exposure device having a fiber optics tube (hereinafter referred to as "FOT") for exposing a photosensitive recording medium to light to form a color image in accordance with an image data inputted to the FOT.
There has been known an image forming apparatus in which an image light is irradiated to a photosensitive and pressure-sensitive recording medium by an exposure device such as a cathode-ray tube (CRT) or the like to form an image on the photosensitive and pressure-sensitive recording medium. On the other hand, a fiber optics tube (FOT) having an optical fiber array provided at an exposing surface thereof has been known as a compact display unit, however, has not been hitherto used as an exposure device for forming an image.
In view of the above, the applicant of this application has proposed an exposure device for exposing a photosensitive recording medium to light using an optic fiber tube to form an image on the photosensitive recording medium as disclosed in Japanese Patent Application No. 63-199279.
The photosensitive recording medium used in the above conventional image forming apparatus comprises a sheet substrate such as PET (polyethylene terephthalate) or the like, and photosensitive microcapsules encapsulating dye precursors which are coated on one surface of the sheet substrate. In this photosensitive recording medium, a sheet substrate of black color is ordinarily used for preventing halation in the photosensitive recording medium due to reflection of light from the sheet substrate, and therefore it is required to irradiate light to the photosensitive recording medium through the microcapsule coating surface thereof. This requirement also requires the optic fiber array of the FOT to be disposed in a confronting relation to the microcapsule coating surface of the photosensitive recording medium. That is, the optic fiber array is disposed so that an image light emitted from the optic fiber array is directly irradiated to the microcapsules coating surface of the photosensitive recording medium. In this case, the optic fiber array must be disposed at an interval away from the microcapsule coating surface of the photosensitive recording medium in order to prevent the microcapsules coated on the sheet substrate from being damaged by a contact between the optic fiber array and the microcapsule coating surface, so that a gap is intentionally provided between the optic fiber array and the microcapsule coating surface of the photosensitive recording medium. Accordingly, it frequently occurs that the light emitted from the optic fiber array is slightly diffused in the gap, so that an image having a deteriorated image quality is formed on the photosensitive recording medium, and a clear color image is not obtained with high resolution.